Klaviyo Inc.

A leading technology company is seeking an experienced Fullstack Software Engineer II to join their SMS International team in London. The successful candidate will work collaboratively to deliver innovative RCS and SMS services, requiring 3-5 years of software engineering experience and proficiency in full stack development. Key technologies include Python, Django, AWS, and Kubernetes. The position offers a competitive salary range of £68,000 - £102,000 GBP and may require occasional travel for team meetings and events.

Software Engineer - SMS International Engineering London, UK About the Role As a Fullstack Software Engineer II joining the SMS International team you will be working with a team of 5 other colleagues to deliver RCS and SMS International expansion to meet the company's objectives. You will get the chance to build brand new services, understand how they fit into the bigger picture and plan how to architect and scale them successfully to serve our customers. Technologies we use (not exhaustive) Python, Django, Go, React, SQS, Celery, MySQL, DynamoDB, Elasticache, Redis Amazon Web Services (EC2, RDS, Aurora, etc.), Terraform, Kubernetes, Splunk, Buildkite, Grafana, Chronosphere and other modern DevOps tools What we are looking for 3-5 years of experience in a software engineering discipline Experience with full stack application development Experience working with both monolithic and microservices architectures Experience with database design that can withstand high query volumes Experience with CI/CD pipelines Experience debugging performance issues and improving application performance An interest and aptitude for collaboration across teams and disciplines Nice to have Experience creating new services with scalability in mind. Exposure to large-scale system design Experience with AWS or any similar cloud provider Communication domain experience Compensation Base Pay Range in Local Currency: £68,000 - £102,000 GBP Benefits This role may require up to 10% travel for purposes such as new hire onboarding, client or partner work if applicable, team meetings, and industry events. Travel is coordinated in advance. IMPORTANT NOTICE: Our company takes the security and privacy of job applicants very seriously. We will never ask for payment, bank details, or personal financial information as part of the application process. All our legitimate job postings can be found on our official career site. Please be cautious of job offers that come from non-company email addresses instant messaging platforms, or unsolicited calls. Klaviyo is committed to a policy of equal opportunity and non-discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law.

At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyo (we call ourselves Klaviyos) brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you're a close but not exact match with the description, we hope you'll still consider applying. Want to learn more about life at Klaviyo? Visit to see how we empower creators to own their own destiny. About the Opportunity At Klaviyo, the Sales team prides itself on being made up of marketing and product experts. While many companies hire pre-sales Solutions Engineers simply to give demos, fill out questionnaires, and explain setups, that approach makes us yawn. We're looking for a Senior Solutions Engineer who brings deep technical mastery, strategic thinking, and the ability to own the most complex, high-stakes Enterprise deals. This is a high-impact individual contributor role for someone who thrives in ambiguity, rolls up their sleeves to master our product at a molecular level, and uses AI and automation to punch above their weight. As a Senior SE, you'll be a trusted advisor to both customers and our sales organization - leading technical strategy in 6-7 figure deals, owning solution design, and setting the standard for Solutions Engineering excellence through your work. What We Do as Solutions Engineers We're technical sellers who drive revenue by winning complex Enterprise deals. Our job is to own the technical win - building champions, proving value, and ensuring prospects choose Klaviyo over the competition. We work directly with customers to architect solutions that integrate seamlessly into their tech stacks, taking a consultant-first approach that builds confidence and secures technical buy-in. Beyond closing deals, we use customer engagements as opportunities to prototype and ship improvements to Klaviyo. Recent team projects include AI-powered demo data generators, a public Chrome extension for troubleshooting API calls, web SDK injectors, and templatized mobile apps that showcase our SDK capabilities. If you're a creator excited by winning high-stakes deals, prototyping technical solutions, and driving strategic revenue outcomes, this could be the role for you. How You'll Make a Difference Lead the Technical Win in High-Stakes, Complex Deals Own technical strategy for the most complex Enterprise opportunities, navigating multi-layered stakeholder environments, competitive pressures, and sophisticated buying processes with minimal oversight Drive advanced technical discovery, uncovering nuanced pain points and proactively identifying differentiation opportunities Host technical workshops that align solutions to business outcomes, demonstrating executive presence and strategic communication Architect and execute Proof of Value plans that secure technical selection over competitors Partner closely with AEs on deal strategy, bringing competitive intelligence and industry expertise to influence outcomes Bring Subject Matter Expertise and Industry Leadership Serve as a domain expert in marketing technology, CDPs, AI-driven personalization, analytics, and eCommerce Act as a go-to resource for competitive and industry landscape questions Build strong relationships with R&D, collaborating to drive positive outcomes and influence Klaviyo's roadmap Contribute high-impact content to the SE Learning Library and mentor peers through example Operate with Deep Technical Mastery and Innovation Become an expert across Klaviyo's platform, from data pipelines and integrations to technical trade-offs between implementations Develop broad, advanced familiarity with web development, APIs, cloud computing, and modern software development practices Confidently coach experienced engineers on complex solution design Leverage AI tools and automation to scale impact and improve customer outcomes Prototype solutions and build proof-of-concepts that clearly demonstrate Klaviyo's differentiation Who You Are Required 5+ years of experience in Solutions Engineering or Pre-Sales, with 3+ years leading technical strategy on high-complexity Enterprise deals (6-7 figures) with minimal oversight Familiarity with AI-assisted development tools (e.g. Codex, Claude Code) and emerging patterns such as MCP Strong domain knowledge in marketing automation, CDPs, eCommerce systems, analytics, or data engineering Advanced discovery and requirements-gathering skills across multi-layered stakeholder environments Executive presence with exceptional communication skills, from executive-level conversations to deep technical discussions Proven ability to manage objections, handle challenging conversations, and deliver strategic insights What Sets You Apart You've used AI to scale your effectiveness through automation, research, solution design, or development You bring deep competitive intelligence and understand the landscape intimately You build strong R&D relationships and drive outcomes through influence rather than authority You roll up your sleeves, dig in, and become the expert You elevate team performance through example and enablement You thrive in ambiguity and fast-moving environments We use Covey as part of our hiring and / or promotional process. For jobs or candidates in NYC, certain features may qualify it as an AEDT. As part of the evaluation process we provide Covey with job requirements and candidate submitted applications. We began using Covey Scout for Inbound on April 3, 2025. Please see the independent bias audit report covering our use of Covey here Our salary range reflects the cost of labour in the country where the job post is advertised. The base salary offered for this position is determined by several factors, including the applicant's job-related skills, relevant experience, education or training, and work location. In addition to base salary, our total compensation package may include participation in the company's annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign-on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility. Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process. Base Pay Range in Local Currency: Get to Know Klaviyo We're Klaviyo (pronounced clay-vee-oh). We empower creators to own their destiny by making first-party data accessible and actionable like never before. We see limitless potential for the technology we're developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators-ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you're ready to do the best work of your career, where you'll be welcomed as your whole self from day one and supported with generous benefits, we hope you'll join us. AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human-in-the-loop). We provide accommodations as needed. Klaviyo is committed to a policy of equal opportunity and non-discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law. IMPORTANT NOTICE: Our company takes the security and privacy of job applicants very seriously. We will never ask for payment, bank details, or personal financial information as part of the application process. All our legitimate job postings can be found on our official career site. Please be cautious of job offers that come from non-company email addresses instant messaging platforms, or unsolicited calls. By clicking "Submit Application" you consent to Klaviyo processing your Personal Data in accordance with our Job Applicant Privacy Notice. If you do not wish for Klaviyo to process your Personal Data, please do not submit an application. You can find our Job Applicant Privacy Notice here and here (FR).

Software Engineer - Catalog Insights - Analytics London, UK At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyos brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you're a close but not exact match with the description, we hope you'll still consider applying. Want to learn more about life at Klaviyo? Visit to see how we empower creators to own their destiny. The Catalog Insights Team's mission is to arm Klaviyo customers with the data they need to drive sustainable business growth through efficient and effective product placement. Beyond analytical views, this team is also highly focused on actionability: finding creative ways for customers to go from catalog insight to revenue-driving marketing action in a matter of clicks. As an Engineer on the Catalog Insights team you can expect to be deeply involved in the technical discussions and delivery of the features our customers need. You'll have ownership of projects that contribute to the team's mission, goals, and roadmap. You'll collaborate alongside technical product owners and product managers to build a product and develop a technical strategy to deliver products that make it easy for users to understand their data and performance. Your tech stack will include Python, Typescript, React, AWS, Kubernetes, Django, and Spark. How You Will Make A Difference Deliver key product capabilities for Catalog Insights to support our recently launched Marketing Analytics product. Design and build systems and data pipelines that process large volumes of data to deliver experiences providing value to Klaviyo customers of all sizes Work cross functionally with product, design, and data science teams to develop product requirements and technical solutions. Own product solutions end-to-end, including technical design, implementation, maintenance, monitoring, and participation in on-call rotations for the services we ship. Have ample opportunities for growth. Who You Are 2+ years experience working in a SaaS product in full stack capacity Proficient in at least one modern programming language Degree or equivalent experience in a software engineering discipline Able to communicate well Able to work with others on a team Able to learn continuously and adapt to a high growth environment Able to stick with and solve difficult problems Excited to learn and understand data visualization in addition to full stack engineering We use Covey as part of our hiring and / or promotional process. For jobs or candidates in NYC, certain features may qualify it as an AEDT. As part of the evaluation process we provide Covey with job requirements and candidate submitted applications. We began using Covey Scout for Inbound on April 3, 2025. Please see the independent bias audit report covering our use of Covey here Our salary range reflects the cost of labour in the country where the job post is advertised. The base salary offered for this position is determined by several factors, including the applicant's job-related skills, relevant experience, education or training, and work location. In addition to base salary, our total compensation package may include participation in the company's annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign-on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility. Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process. Base Pay Range in Local Currency: Get to Know Klaviyo We're Klaviyo (pronounced clay-vee-oh). We empower creators to own their destiny by making first-party data accessible and actionable like never before. We see limitless potential for the technology we're developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators-ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you're ready to do the best work of your career, where you'll be welcomed as your whole self from day one and supported with generous benefits, we hope you'll join us. AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human-in-the-loop). We provide accommodations as needed. Klaviyo is committed to a policy of equal opportunity and non-discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law. IMPORTANT NOTICE: Our company takes the security and privacy of job applicants very seriously. We will never ask for payment, bank details, or personal financial information as part of the application process. All our legitimate job postings can be found on our official career site. Please be cautious of job offers that come from non-company email addresses instant messaging platforms, or unsolicited calls. By clicking "Submit Application" you consent to Klaviyo processing your Personal Data in accordance with our Job Applicant Privacy Notice. If you do not wish for Klaviyo to process your Personal Data, please do not submit an application. You can find our Job Applicant Privacy Notice here and here (FR). We operate a hybrid working culture here at Klaviyo in EMEA whereby people spend their time working from the office and remotely. For this role, the expectation is to be in our London office for 3 days a week. Is this setup something you are comfortable with? Would you be willing to relocate if the role requires it? Do you currently have legal work authorization in the country where this position is based? Would you, now or in the future, require immigration sponsorship for work authorization? How did you hear about us? Enter the verification code sent to to confirm you are not a robot, then submit your application. Security Code

A leading data-driven marketing platform in London is looking for a Software Engineer for its Catalog Insights Team. Your role includes delivering key product capabilities for Marketing Analytics, designing data processing pipelines, and ensuring end-to-end ownership of product solutions. The ideal candidate has over 2 years of experience in SaaS and a strong skill set in programming, including Python and React. This position offers a hybrid work model requiring 3 days at the office each week.

A leading marketing technology firm in Greater London is seeking a Senior Solutions Engineer to lead technical strategy in high-stakes Enterprise deals. This role requires a minimum of 5 years in Solutions Engineering and deep knowledge of marketing automation and analytics. The ideal candidate will drive technical discovery and collaborate closely with sales teams. This position supports a hybrid work environment and promotes a culture of inclusivity and innovation.

A prominent technology company in London is looking for a Senior Software Engineer for their Internationalisation Platform. The role involves leading complex projects that enhance internationalisation features. The ideal candidate will have over 5 years of software development experience, a strong focus on customer needs, and a collaborative approach. Competitive salary, equity package, and health benefits are offered, along with a culture that prioritizes psychological safety and work/life balance.

Senior Software Engineer, Internationalisation Platform London, UK At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyos brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you're a close but not exact match with the description, we hope you'll still consider applying. Want to learn more about life at Klaviyo? Visit to see how we empower creators to own their destiny. Why You Should Join the Internationalisation Platform Team The i18n Platform team owns all the ways we create, process and deliver internationalisation features for our users at Klaviyo. As a Senior Software Engineer, you will be a key contributor and mentor leading complex, multi-component projects across the i18n platform. You will be involved in how we manage translations, deliver new localisation features, handle multiple currencies, and improve our internationalisation processes. You can look forward to being a part of a highly technical team with significant domain expertise. We oversee tools and services that are leveraged across the organization from the frontend UI to backend data. The team also owns and orchestrates several services to manage the pipeline of translations with our localisation team. As we look toward the next 6-12 months, we aim to focus on delivering LLM workflows to improve our translation capabilities, increase the availability of our Smart Translations product, and develop new features for handling different currencies in multiple regions. Why you should join We foster a culture of psychological safety, collaboration, and work/life balance through flexible hours and structured on-call rotations. We practice a "you make it, you support it" attitude to our products and provide on-call support in case of incidents. We offer compensation for on-call rotations and expect to maintain a very low number of incidents requiring call-out. New engineers are onboarded to the on-call rotation gradually, typically joining the active rotation after their first 6 months and thorough training. We are committed to your growth. You will be paired with a dedicated mentor and given time for focused skill development, including opportunities to attend relevant industry conferences and a growing suite of learning & development opportunities. We enjoy a high degree of autonomy to generate innovative solutions across the entire system, learning directly from customers and suggesting cool new approaches. Free lunch at our Aldgate office three times a week Highly competitive salary, equity package, and comprehensive health benefits. How You Will Make a Difference You will lead and drive the design and execution of complex, business-critical projects across the Internationalisation platform. You will be responsible for implementing new functionality and establishing design patterns for complex, multi-component systems. You will take full lifecycle ownership of features and projects, driving requirement refinement and setting the pace for all phases of execution. You will proactively collaborate with cross-functional partners to influence product requirements and communicate technical needs to other teams. You will be an active participant in all team processes and accountable for meeting the health and operational excellence (SLOs) of your area of ownership. You will help interview new engineering team members and actively mentor junior engineers in your product area. What we are looking for A strong interest in internationalisation, localisation, and translation. A desire to serve our international customers and expand Klaviyo's capabilities. 5+ years of demonstrable experience delivering high-quality, customer-facing software. Deep understanding of complex systems (or similar large-scale distributed systems) and strong systems thinking, with a proven ability to scale, observe, and maintain services. Familiarity with full stack development concepts and a strong aptitude to learn. Experience working with both monolithic and microservices architectures Experience with database design that can withstand high query volumes Experience debugging performance issues and improving application performance An interest and aptitude for collaboration across teams and disciplines An understanding of challenges in developing software across multiple languages and catering to non English speaking users Thrives in a fast paced, customer focused, and strategic environment. A track record of prioritizing the needs and success of the company overall above the immediate needs of the team. Nice to Have Proven experience with large-scale system design and driving the technical/architectural evolution of a product area. Experience with AWS or any similar cloud provider Experience with billing systems in multiple currencies Technologies we use (not exhaustive) REST, GraphQL, JSON Schema, JSON:API CDNs (Fastly, Cloudflare) GitHub, BuildKite MySQL, Redis, Pulsar, Memcache DeepL, Smartling, Stripe Amazon Web Services (EC2, RDS, Aurora, AWS Translate, etc.), Terraform, Kubernetes, Splunk, Chronosphere, Cortex, DX, and other modern DevOps tools Our salary range reflects the cost of labour in the country where the job post is advertised. The base salary offered for this position is determined by several factors, including the applicant's job related skills, relevant experience, education or training, and work location. In addition to base salary, our total compensation package may include participation in the company's annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility. Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process. Get to Know Klaviyo We're Klaviyo (pronounced clay vee oh). We empower creators to own their destiny by making first party data accessible and actionable like never before. We see limitless potential for the technology we're developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators-ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you're ready to do the best work of your career, where you'll be welcomed as your whole self from day one and supported with generous benefits, we hope you'll join us. AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human in the loop). We provide accommodations as needed. Klaviyo is committed to a policy of equal opportunity and non discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law. IMPORTANT NOTICE: Our company takes the security and privacy of job applicants very seriously. We will never ask for payment, bank details, or personal financial information as part of the application process. All our legitimate job postings can be found on our official career site. Please be cautious of job offers that come from non-company email addresses instant messaging platforms, or unsolicited calls. By clicking "Submit Application" you consent to Klaviyo processing your Personal Data in accordance with our Job Applicant Privacy Notice. If you do not wish for Klaviyo to process your Personal Data, please do not submit an application. You can find our Job Applicant Privacy Notice here and here (FR).